|Publication number||US7918296 B2|
|Application number||US 12/210,874|
|Publication date||Apr 5, 2011|
|Filing date||Sep 15, 2008|
|Priority date||Sep 15, 2008|
|Also published as||US20100065355|
|Publication number||12210874, 210874, US 7918296 B2, US 7918296B2, US-B2-7918296, US7918296 B2, US7918296B2|
|Inventors||Suresh B. Reddy|
|Original Assignee||Caterpillar Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (153), Referenced by (8), Classifications (32), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This patent disclosure relates generally to systems and methods for electric drives and, more particularly, to cooling systems and methods for cooling electric drive components of a machine.
Cooling systems typically use circulating fluid or coolant to absorb heat from various components of the machine. The circulating fluid absorbs heat from various components thus removing it therefrom as it flows through the cooling system. The heat or thermal energy collected is removed from the fluid, typically in a radiator or another similar device.
Known cooling systems are effective in cooling various components of a vehicle but have limitations as to their operating temperatures and system requirements. For example, the heat absorption capacity of a liquid-coolant system depends on the flow rate of the coolant as well as on the total volume of coolant in the system. One disadvantage of liquid-coolant systems is their implementation in applications having weight restrictions because of the weight of the fluid and related cooling system components that are carried onboard the vehicle. In applications having both weight restrictions in addition to requiring the removal of large amount of heat, adequate cooling using a liquid-based cooling system may not be practical and may also add weight and complexity to the vehicle.
Another disadvantage of liquid-coolant systems is the electrical conductivity of the cooling medium. Because water is typically a main component of a liquid-coolant mixture, the electrical conductivity that is inherent to such mixtures makes their use unsuitable for cooling electrical components internally, such as generators and motors. Electric drive vehicles must rely on use of other mediums, such as air, for cooling. As is known, the heat capacity of air is lower than that of water or a liquid-based coolant, which means that a large volume of air must be used to match the cooling capacity of a liquid-based coolant. The energy expended to move large volumes of air around and through various components of the vehicle reduces the fuel or energy efficiency of the vehicle. Moreover, cooling systems using air, especially when used to cool more than one areas or components of the vehicle, require ducts that extend to the various components of the vehicle. Such ducts are usually large to accommodate the high volumes of air flowing to cool each components, which makes the routing of the ducts and the positioning of components in the design of the vehicle more complex and costly.
The disclosure describes, in one aspect, a cooling system for cooling components of an electric drive system. The cooling system includes a cooling duct extending between a first component and a second component. A motor driven fan creates an airflow within the duct. A first temperature sensor measures a first temperature of the first component and a second temperature sensor measures a second temperature of the second component. An electronic controller receives the first temperature and calculates a first temperature difference between the first temperature and the first temperature limit to generate a first command for the motor. The electronic controller receives the second temperature and calculates a second temperature difference between the second temperature and the second temperature limit to generate a second command for the motor. The controller then selects the greater of the first command and the second command to yield the maximum command, and controls the motor based on the maximum command.
In another aspect, the disclosure describes a machine having an electric drive system. The electric drive system includes an engine connected to a generator. The generator has an electrical output connected to a rectifier. The rectifier is connected to an inverter, which is connected to an electric drive motor. The machine further includes a cooling duct in fluid communication with a first component and a second component. A fan motor operates a blower disposed within the cooling duct. A first temperature sensor measures a first component temperature and provides a first component temperature sensing signal. A second temperature sensor measures a second component temperature and provides a second component temperature sensing signal. An electronic controller receives the first component temperature sensing signal and the second component temperature sensing signal, calculates a first difference between the first component temperature and a first component temperature limit to generate a first airflow command based on the first difference, calculates a second difference between the second component temperature and a second component temperature limit to generate a second airflow command based on the second difference, compares the first airflow command with the second airflow command to yield a maximum desired airflow, and commands the fan motor to operate such that the maximum desired airflow is generated within the cooling duct.
In yet another aspect, the disclosure describes a method of operating a blower disposed in a convective cooling system associated with a first component and a second component of a machine. The cooling system includes a cooling duct that directs a cooling flow of air toward the first component and the second component, and a blower operating under the control of a controller to direct a cooling flow of air through the cooling duct. The method includes sensing a first temperature of the first component and providing a first temperature signal indicative of the first temperature, and sensing a second temperature of the second component and providing a second temperature signal indicative of the second temperature. The first temperature signal is compared with a first temperature limit to yield a first temperature difference, and a first desired airflow is calculated based on the first temperature difference. The second temperature signal is compared to a second temperature limit to yield a second temperature difference, and a second desired airflow based on the second temperature difference. The greater of the first desired airflow and the second desired airflow is selected to yield a maximum desired airflow, and the blower is operated to generate a flow of air in the cooling duct that is at least equal to the maximum desired airflow.
This disclosure relates to systems and methods for cooling drive components of an electric drive machine or vehicle. The disclosure that follows uses an example of a direct series electric drive vehicle having an engine connected to a generator for producing electrical power that drives the vehicle. In the exemplary embodiments presented, heat produced by friction or electrical energy passing through electric drive components when the machine is operating is removed and expelled to the environment. The systems and methods disclosed herein have applicability to other electric drive vehicles. Additional examples for an air cooling system for an electric drive machine can be seen in U.S. patent application Ser. No. 12/150,222, which was filed on Apr. 25, 2008, and titled “Air Cooling System for Electric Drive Machine,” and which is incorporated herein in its entirety by reference. In general, a machine or vehicle may include an electric drive with power stored in one or more batteries or other storage devices, instead of being generated by an engine driven generator. This embodiment may store excess power produced during retarding in the batteries or other mechanical energy storage devices and arrangements rather than dissipating it in the form of heat.
A front view of the off-highway truck 101 is shown in
The off-highway truck 101 is a direct series electric drive machine, which in this instance refers to the use of more than one source or form of power to drive the drive wheels 108. A block diagram for the direct series electric drive system of the machine 100, for example, the off-highway truck 101, is shown in
When the off-highway truck 101 is propelled, the engine 202 generates mechanical power that is transformed into electrical power, which is conditioned by various electrical components. In an illustrated embodiment, such components are housed within a cabinet 114 (
Specifically, when the machine 100 is retarding, the kinetic energy of the machine 100 is transferred into rotational power of the drive wheels that rotates the motors 210, which act as electrical generators. The electrical power generated by the motors 210 has an AC waveform. Because the inverter circuit 208 is a bridge inverter, power supplied by the motors 210 is rectified by the inverter circuit 208 into DC power. Dissipation of the DC power generated by the motors 210 produces a counter-rotational torque at the drive wheels 108 to decelerate the machine. Dissipation of this DC power may be accomplished by passing the generated current rectified by the inverter circuit 208 through a resistance. To accomplish this, a retarder arrangement 213 may include a first resistor grid 214, described in greater detail below, that is arranged to receive current from the inverter circuit 208 via a switch 216. When the switch 216 is closed, the electrical power corresponding to the current generated by the motors 210 may pass through the first resistor grid 214 and be dissipated as heat. Additionally, excess electrical power is also dissipated as heat as it passes through a second resistor grid 218, which is arranged to receive electrical power via a chopper circuit 220. The chopper circuit 220 operates to selectively route a portion of the developed electrical power through the second resistor grid 218. One embodiment for the drive and retarding system is described in more detail below.
A block diagram of the direct series electric drive system of the off-highway truck 101, as one example for the machine 100, is shown in
In one embodiment, the generator 204 is a three-phase alternating current (AC) synchronous generator having a brushless, wound rotor. The generator 204 has an output 301 for each of three phases of alternating current being generated, with each output having a respective current transducer 306 connected thereto. The rotor of the generator 204 (shown in
In the illustrated embodiment, the rotating rectifier 302 includes a rotating exciter armature 302A that is connected to a series of rotating diodes 302B. The three current outputs of the generator 204, which are collectively considered the output of the generator 204, are connected to a rectifier 206. Other generator arrangements may alternatively be used.
The rectifier 206 converts the AC power supplied by the generator 204 into DC power. Any type of rectifier 206 may be used. In the example shown, the rectifier 206 includes six power diodes 310 (best shown in
During operation, a voltage is supplied across the first and second rails of the DC link 312 by the rectifier 206 and/or an inverter circuit 208. One or more capacitors 320 may be connected in parallel with one or more resistors 321 across the DC link 312 to smooth the voltage V across the first and second rails of the DC link 312. The DC link 312 exhibits a DC link voltage, V, which can be measured by a voltage transducer 314, and a current, A, which can be measured by a current transducer 316, as shown in
The inverter circuit 208 is connected in parallel with the rectifier 206 and operates to transform the DC voltage V into variable frequency sinusoidal or non-sinusoidal AC power that powers, in this example, two drive motors 210 (
The inverter circuit 208 can control the speed of the motors 210 by controlling the frequency and/or the pulse-width of the AC output. The drive motors 210 may be directly connected to the drive wheels 108 or, as in the example shown in
In alternative embodiments, the engine 202 and generator 204 are not required to supply the power necessary to drive the drive motors 210. Instead, such alternative embodiments use another source of power, such as a battery or contact with an electrified rail or cable. In some embodiments, one drive motor 210 may be used to power all drive wheels of the machine, while in other embodiments, any number of drive motors may be used to power any number of drive wheels, including all wheels connected to the machine.
Returning now to the block diagrams of
The generated AC electrical power can be converted into DC electrical power through the inverter circuit 208 for eventual consumption or disposition, for example, in the form of heat. In an illustrated embodiment, a retarder arrangement 213 consumes such electrical power generated during retarding. The retarder arrangement 213 can include any suitable arrangement that will operate to dissipate electrical power during retarding of the machine. In the exemplary embodiments shown in
When the machine 100 is to operate in a retarding mode, the first resistor grid 214 is connected between the first and second rails of the DC link 312 so that current may be passed therethrough. When the machine 100 is being propelled, however, the first resistor grid 214 is electrically isolated from the DC link 312 by two contactors or bipolar automatic switches (BAS) 216. Each BAS 216 may include a pair of electrical contacts that are closed by an actuating mechanism, for example, a solenoid (not shown) or a coil creating a magnetic force that attracts the electric contacts to a closed position. The BAS 216 may include appropriate electrical shielding and anti-spark features that can allow these items to operate repeatedly in a high voltage environment.
When the machine 100 initiates retarding, it is desirable to close both BAS 216 within a relatively short time period such that the first resistor grid 214 is placed in circuit between the first and second DC rails to begin energy dissipation rapidly. Simultaneous actuation or actuation at about the same time, such as, within a few milliseconds, of the pair of BAS 216 may also advantageously avoid charging the first resistor grid 214 and other circuit elements to the voltage present at the rails of the DC link 312. The pair of BAS 216 also prevents exposure of each of the BAS 216 or other components in the system to a large voltage difference (the voltage difference across the DC link 312) for a prolonged period. A diode 334 may be disposed in parallel to the first resistor grid 214 to reduce arcing across the BAS 216, which also electrically isolates the first resistor grid 214 from the DC link 312 during a propel mode of operation.
When the machine 100 is retarding, a large amount of heat can be produced by the first resistor grid 214. Such energy, when converted to heat, must be removed from the first resistor grid 214 to avoid an overheating condition. For this reason, a blower 338, driven by a motor 336, operates to convectively cool the first resistor grid 214. There are a number of different alternatives available for generating the power to drive the motor 336. In this embodiment, a DC/AC inverter 340 is arranged to draw power from voltage-regulated locations across a portion of the first resistor grid 214. The DC/AC inverter 340 may advantageously convert DC power from the DC link 312 to 3-phase AC power that drives the motor 336 when voltage is applied to the first resistor grid 214 during retarding.
In the illustrated embodiment, the BAS 216 are not arranged to modulate the amount of energy that is dissipated through the first resistor grid 214. During retarding, however, the machine 100 may have different energy dissipation requirements. This is because, among other things, the voltage V in the DC link 312 should be controlled to be within a predetermined range. To meet such dissipation requirements, the second resistor grid 218 can be exposed to a controlled current during retarding through action of the chopper circuit 220. The chopper circuit 220 may have any appropriate configuration that will allow modulation of the current supplied to the second resistor grid 218. In this embodiment, the chopper circuit 220 includes an arrangement of transistors 342 that can, when actuated according to a desired frequency and/or duration, modulate the current passed to the second resistor grid 218. This controls the amount of energy dissipated by the second resistor grid 218 during retarding. The chopper circuit 220 may additionally include a capacitor 344 that is disposed between the first and second rails of the DC link 312 and that regulates the voltage input to the chopper circuit 220. A switched diode 346 may be connected between the second resistor grid 218 and the DC link 312 to protect against short circuit conditions in the DC link 312.
The passage of current through the second resistor grid 218 will also generate heat, necessitating cooling of the second resistor grid 218. In this embodiment, the first and second resistor grids 214 and 218 may both be located within the blower housing 116 (also shown in
The embodiment for a drive system shown in
Various electrical components of the drive system may, or contain within them other components that, generate heat during operation. For example, the cabinet 114 may house the rectifier circuit 206 (
In the embodiment shown in
One component arranged to receive air from the cooling duct assembly is the generator 204. Air travelling through the main portion 412 may be partially or entirely routed toward the generator 204. The generator 204 may have appropriate internal passages that permit airflow therethrough for cooling. The generator 204 may alternatively have external features, such as fins, which may promote the flow of air over surfaces of the generator 204 to promote convective cooling.
The main portion 412 of the cooling duct assembly 408 may further be fluidly connected to an internal cavity 414 that is defined within the hollow axle assembly 404. In one embodiment, the internal cavity 414 at least partially encloses or contains the motors 210. Air travelling through the main portion 412 may be routed to the internal cavity 414, either directly from the main portion 412, or alternatively via one or more runners 416, which are optional. Such air flow convectively cools the motors 210. The airflow within the internal cavity 414, and the heat it has absorbed along its path through the cooling duct assembly 408, may be expelled into the environment via an opening 418 formed in the hollow axle assembly 404. Alternatively, heat may be expelled via other openings, for example, a pair of openings 420 formed close to each end of the hollow axle assembly 404.
A block diagram showing the various components and systems that are associated with a cooling duct arrangement in accordance with the disclosure is shown in
In the disclosed embodiment, the fan motor 512 is a hydrostatic motor that is disposed within the fan portion 508 and operates by a flow of hydraulic fluid passing through conduits 514. The circulating flow may be impelled by a pump 516. The speed of the fan motor 512 may be controlled by a solenoid valve 518 and may be measured by a sensor (not shown). The control arrangement for controlling the speed of the fan motor 512 may be any number of arrangements. For example, the solenoid valve 518 may shunt or otherwise restrict a portion of the flow of fluid impelled by the pump 516 from reaching the fan motor 512. Similarly, the pump 516 may be driven by the engine 519 of the machine via an input shaft 520 or by any other appropriate method.
During operation, the fan 510 creates air flow through the cooling duct 502. Such airflow through the cooling duct 502 is denoted by dot-dash-dot lined and open headed arrows. This flow of air may enter through the inlet opening 504 and travel the entire length of the cooling duct 502 before exiting via one or more outlet opening(s) 522 defined in the cooling duct 502. Along its path, the airflow may pass over and/or through various components that require convective cooling.
The cooling duct 502 may form a generator portion 524 that at least partially envelopes a portion or passes through a portion of a generator 526 of the machine. The generator 526 may be the generator 204 shown in
The cooling duct 502 may further be fluidly connected to the internal cavity 414 defined within the hollow axle assembly 404 (
The airflow within the cooling duct 502, having passed over the various components of the drive system described above, may be expelled into the environment through the one or more outlet opening(s) 522. The exiting airflow carries with it the thermal energy that was removed when the various components that communicate with the cooling duct 502 were convectively cooled. In the embodiment shown in
The cooling system thus far has been described relative to its structure. Activation of the fan 510 when it is determined that various components require cooling is also described herein. It can be appreciated that continuous operation of the fan 510 would likely reduce the fuel efficiency of the machine 100. Hence, the fan 510 should operate in a mode that is both fuel efficient and which provides adequate cooling to the various components of the machine. This can be accomplished via an electronic controller 540, which is disposed to receive temperature information from the various components that are associated with the cooling duct 502. The controller 540 operates in a logical fashion in response to these data to control the operation of the fan 510.
The electronic controller 540 is connected to various temperature sensors or transducers throughout the system. Examples of such sensors and their placement, which are meant as illustrative and non-limiting examples, include a chopper circuit temperature sensor 542 disposed proximate to the chopper circuit 220. The inverter circuits 208 may include one or more inverter temperature sensor(s) 544 (two shown) that are appropriately positioned in areas thereof that are sensitive to high temperatures. Such locations may be adjacent to electronic components that include integrated control circuits, transistors, and so forth. An ambient temperature sensor 546 may be optionally installed within the cabinet 114 to measure the temperature of air (T-AMB) that circulates within the cabinet 114. Air circulating within the cabinet 114, in one embodiment, is air that eventually forms the airflow passing through the cooling duct 502.
Other components of the drive system may also include temperature sensors to measure the temperature of various internal components thereof. For example, the generator 526 may include a generator winding temperature sensor 548 that is disposed to measure the temperature of the windings 528 (T-GW) of the generator 526. A rotor bearing temperature sensor 550 is disposed to measure the temperature of the rotor bearings 530 (T-GB). Similarly, each drive motor 532 may include a respective motor winding temperature sensor 552, disposed to measure the temperature of the windings 534 (T-MW1 and T-MW2) of each motor 532. A respective motor bearing temperature sensor 554 is disposed to measure the temperature of the bearings 536 (T-MB1 and T-MB2) in each motor 532.
These various temperature sensors may be operatively connected to the electronic controller 540 and disposed to communicate information indicative of the various temperatures being measured. The interconnections between the electronic controller 540 and various sensors in the cooling system are denoted by dotted lines in
A block diagram for a control algorithm 600 operating within the electronic controller 540 is shown in
The outer loop 602 may operate to determine a setpoint and, therefore, the initiation of operation of the fan motor 512. The inner loop 604 may adjust various parameters that control the operation of the fan motor 512. Other algorithms or sub-routines may operate in conjunction with the control algorithm 600. For example, various diagnostic and fault detection sub-routines may be utilized to determine whether certain components or sensors of the drive system are operational. Such algorithms are denoted generically by reference numeral 606 in
Turning now to one embodiment of the outer loop 602, an algorithm receives the various temperature readings of the temperature sensors disposed in the system. For example, and in conjunction with
During normal operation or operation in the absence of any fault detection, the parameters listed thus far, along with the engine speed (RPM), may be used to determine a desired fan speed or airflow rate command. This command may be appropriately set such that the airflow generated within the cooling system in response to the command is adequate to maintain all cooled components within a normal operating temperature range.
Accordingly, an output node 608 of the outer loop 602 may communicate an airflow request to the inner loop 604. The inner loop 604 may control the speed of the fan motor, for example, the fan motor 512 (
The inner loop 604 further bases the determination of the command signal to the solenoid on the engine speed (RPM). This is due to the face that the engine 519 may be used to drive the pump 516 that is generating the flow of hydraulic fluid operating the fan motor 512, as shown in
In one embodiment, control of the motor and fan is accomplished in an “open loop” fashion. This means that the airflow request 608 from the outer loop 602 may be set independently of the operating conditions of the fan motor 512. In this embodiment, feedback from the fan motor 512 may be considered in the fanctioning of the inner loop 604.
The summation function 712 may receive other terms, in this case, the maximum 714 of two feed-forward terms 716 and 718, indicative of the expected airflow that the first and second motors may require under a given set of operating circumstances of the machine. Such feed forward terms can improve the time response of a PI control. The output of the summation function 712, which is also the output of the first sentinel 702, may be a first desired airflow request 720.
In a similar fashion, other sentinel functions are used to determine respective desired airflow requests that are indicative of their respective component's cooling requirements. More specifically, a second sentinel 722 may be dedicated to monitoring the temperature of the bearings in the drive motors. The second sentinel 722 may receive readings indicative of the actual temperature experienced by the motor bearings (T-MB1 and T-MB2), discern the maximum value at 724, compare it to a threshold value 726, and use an additional PI control 728. This additional PI control 728 may generate an output that is added to additional feed forward terms 736 and 738 to eventually generate a second desired airflow request 740.
In a similar fashion, a third sentinel 742 may be dedicated to monitoring the generator's winding temperature (T-GW) to yield a third desired airflow request 744. A fourth sentinel 746 may also monitor the generator's bearing temperature (T-GB) to yield a fourth desired airflow request 748. Other sentinels, which are not described in detail for the sake of brevity but that operate similarly to the sentinels already described, may monitor the temperature of the chopper circuit(s) at 750, the inverter(s) at 752, and so forth. Each sentinel generates a desired air flow, shown as 754 for sentinel 750 and as 756 for sentinel 752, based on a specific temperature limit for each components (denoted generically as “LIMIT”). Each sentinel uses feed-forward (“FF”) for control. Each desired airflow 720, 740, 744, 748, 754, and 756, may be input into a comparator 758 which may select the maximum desired airflow or airflow request output of the outer loop 602.
As can be appreciated, the outer loop 602 described thus far operates to continuously monitor the temperature of each component of interest in the drive system, and compares the component temperatures to individual temperature limits. The outer loop 602 can be tailored to accommodate any special design limits of the components. The outer loop is further capable of generating an airflow indication that would be required to effectively cool each of the components. Because all the components are disposed in series within the same cooling duct, and because one fan operates to cool all the components, the highest airflow command is selected and communicated to the inner loop 604. The inner loop 604, in turn, delivers this cooling airflow by appropriately commanding the operation of the fan.
A second embodiment for a controller 800 is shown in
The control module 800, which is shown included within the outer loop 602 (
The error or difference is first multiplied by a proportional gain (Kp) 806. The proportional gain Kp may be a constant or variable value. In this embodiment, the proportional gain Kp is the result of a function or calculation 808 that calculates the proportional gain Kp based on the magnitude of the difference between the input temperature and the desired temperature, and the magnitude of the input temperature T-MW1. This relationship may be used to scale the proportional gain Kp such that an improved time response of the PI control can be achieved. The difference is also input into an integrator loop, which includes an inverter 810, an integral gain (Ki) multiplier 812, and an anti-windup integral gain divider (1/Ki) 814. The proportional and integral terms of the PI control are added to one another, and the result is added to a feed forward term 816. The feed forward term 816 may be obtained by a function or lookup table 818 that determines the feed forward term 816 based on one ore more drive parameters of the machine. These drive parameters may include the operating torque of the drive motors, the speed of the motors, the voltage being commanded to the motors, the current passing through the motors, the voltage of the DC link, the voltage commanded to the DC link, the current passing through the DC link, the engine speed, the generator excitation voltage, and/or other parameters.
The sum of the proportional, integral, and feed forward terms yields a desired blower speed 820 that would be required, in this instance, to provide adequate cooling for the windings of the drive motor. A limiter 821 can be used to ensure that the desired blower speed 820 is always within the operating range of the blower. The limiter 821 may set upper and lower limits to the desired blower speed 820 that are either constant values or variable values that are based on environmental parameters, for example, the barometric pressure (BP), the ambient temperature (T-AMB), or machine operating parameters, for example, the engine speed (RPM), and so forth.
The remaining components of the drive system with temperatures being monitored may be arranged with the same or similar control modules as the control module 800. The remaining modules 822 are shown combined and denoted by the same reference numeral for the sake of simplicity. Each of the remaining modules 822 may output a desired blower speed, yielding a plurality of desired blower speeds 824. The desired blower speeds 820 and 824 are input to a comparator 825 that operates to select the maximum desired blower speed 826 as an output, in this embodiment, of the outer loop 602. As can be seen in the figure, the maximum desired blower speed 826 may be used as an anti-windup parameter for each integrator.
The maximum desired blower speed 826 is input to the inner loop 604, which includes a PI control that controls the solenoid valve 518 (as shown in
The output of the inner loop 604 is a command 836 to the solenoid controlling the flow of hydraulic fluid to the blower motor, but may alternatively be any other type of command signal that controls the motor directly or through another device, such as a chopper circuit controlling an electric motor. This command may be limited in a limiter 838 that may be included within the inner loop 604. The limiter 838 may limit the command 836 to be between upper and lower limits that can either be constant values or variable values that are determined based on engine speed (RPM). Moreover, the command 836 may be augmented by a feed forward term 840 that is determined by a table or function 842 based on the maximum desired blower speed 826 to provide stability to the control of the system.
The present disclosure is applicable to many machines and many environments. One exemplary machine suited to the disclosure is large off-highway trucks, such as dump trucks. Exemplary off-highway trucks are commonly used in mines, construction sites and quarries. The off-highway trucks may have payload capabilities of 100 tons or more and travel at speeds of 40 miles per hour or more when fully loaded. The trucks operate in a variety of environments and must be able to cope with high ambient temperatures.
The embodiments for drive system cooling arrangements and methods disclosed herein have universal applicability of various applications having one or more electric drive system components being actively cooled by forced convection. One can appreciate that the cooling duct disclosed herein may be designed to deliver a flow of cooling air to various components of a vehicle that are disposed in any arrangement. Similarly, the methods and control algorithms disclosed herein are capable of controlling the operation of a cooling fan or blower such that the individual cooling needs of one or more components can be accommodated while still promoting operation of the machine in a fuel or energy efficient manner.
Moreover, the methods and systems described above can be adapted to a large variety of machines and tasks. For example, backhoe loaders, compactors, feller bunchers, forest machines, industrial loaders, skid steer loaders, wheel loaders and many other machines can benefit from the methods and systems described.
It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.
Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.
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|U.S. Classification||180/68.3, 180/68.2|
|Cooperative Classification||B60K2001/003, B60W2510/081, B60K6/46, B60W20/00, B60Y2200/412, B60L2240/423, B60K7/0007, B60L2240/441, B60L2240/421, B60W2510/0676, B60K11/06, B60K11/08, B60W10/30, B60Y2200/142, Y02T10/6217, B60K1/02, B60W2510/083, B60K7/0023, B60L2240/445, Y02T10/642, B60K7/0015, B60Y2200/14, B60W2510/0638|
|European Classification||B60K11/06, B60K11/08, B60W10/30, B60K1/02, B60K6/46, B60K7/00P|
|Oct 14, 2008||AS||Assignment|
Owner name: CATERPILLAR INC.,ILLINOIS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:REDDY, SURESH B.;REEL/FRAME:021680/0790
Effective date: 20080915
Owner name: CATERPILLAR INC., ILLINOIS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:REDDY, SURESH B.;REEL/FRAME:021680/0790
Effective date: 20080915
|Sep 24, 2014||FPAY||Fee payment|
Year of fee payment: 4